Herbicidally-Active fatty acid allphatic amine salts

ABSTRACT

The subject invention pertains to novel methods and compositions utilizing novel fatty acid salts which exhibit excellent herbicidal activity in controlling unwanted vegetation. The novel compositions and methods described here facilitate effective weed control using a water soluble aliphatic amine salt of a fatty acid.

This application is a continuation of application Ser. No. 08/385,218,filed Feb. 8, 1995, abandoned, which is a continuation of applicationSer. No. 07/796,161, filed Nov. 22, 1991, abandoned.

BACKGROUND OF THE INVENTION

Weeds cost farmers billions of dollars annually in crop losses and inthe expense of keeping weeds under control. Much of the cost ofintertillage of row crops, maintenance of fallow, seedbed preparation,and seed cleaning is chargeable to weed control. Suppression of weedsalong highways and railroad right-of-ways, and in irrigation ditches,navigation channels, yards, parks, grounds, and home gardens also isexpensive. Ragweed pollen is the source of annual periodic distress toseveral million hayfever sufferers. Poison ivy, poison oak, poisonsumac, nettles, thistles, sandburs, and puncturevine also bring pain tomillions. Weeds also serve as hosts for other crop diseases as well asfor insect pests.

The losses caused by weeds in agricultural production environmentsinclude decrease in crop yield, reduced crop quality, increasedirrigation costs, increased harvesting costs, decreased land value,injury to livestock, and crop damage from insects and diseases harboredby the weeds.

Chemical herbicides have provided an effective method of weed control;however, the public has become concerned about the amount of residualchemicals which might be found in food, ground water, and theenvironment. Stringent new restrictions on the use of herbicides and theelimination of some effective herbicides from the market place couldlimit economical and effective options for controlling costly weeds.Additionally, the visually apparent phytotoxic effects of some systemicherbicides appear very slowly on the target weeds, so pesticide usersoften seek methods by which the apparent speed of action of theherbicide is increased.

Recently, salts of fatty acids, primarily sodium or potassium fatty acidsalts, have been used commercially as pesticides. Compositions havingexcellent pesticidal properties which exploit these salts are availablecommercially from Safer, Inc., under the trademark SAFER INSECTICIDALSOAP. A herbicidally active composition utilizing partially saponifiedfatty acids as the active ingredient is sold by Safer, Inc. under thetrademark SHARPSHOOTER. These fatty acid compositions are effective,naturally occurring pesticides which have no known long termenvironmental effects. Although fatty acid salts have herbicidalactivity, it would be desirable to provide an alternative compositionhaving an unsaponified active ingredient while maintaining theenvironmental compatability of the pesticide and reducing the eye andskin irritancy of the product.

U.S. Pat. Nos. 2,626,862; 4,975,110; and 5,035,741 describe certainfatty acid compositions useful as herbicides. These documents mentionthe use of salts of fatty acids. Specifically, "saponified" fatty acidsare discussed. Saponification means "to form the sodium or potassiumsalt of a fatty acid." It stems from the soap making industry whereanimal fats (esters of fatty acids and glycerol) are hydrolyzed insodium or potassium hydroxide to form the sodium or potassium salts ofthe fatty acids (soaps) and free glycerol. Mixing sodium or potassiumhydroxide with a free fatty acid to form the salt is also calledsaponification. "Complete" saponification means that 100% of the fattyacid is converted to the salt; "partial" saponification means that <100%of the acid is converted to the salt. This means there is a mixture ofthe free fatty acid and the fatty acid salt. U.S. Pat. No. 4,975,110indicates that the free fatty acid form is preferable to fatty acidsalts for use as a herbicide. These patents also teach that the properformulation of a fatty acid herbicide requires one or more surfactants.

BRIEF SUMMARY OF THE INVENTION

This invention concerns novel compositions and methods for selective ornon-selective control of plants. We have discovered that application toweeds of aliphatic amine salts of one or more substituted (orunsubstituted) saturated (or unsaturated) fatty acids results in theeffective control of a broad range of plants. The fatty acids of thesubject invention can be from about C7 to about C20 and can be, forexample, in the epoxide, cyclopropane, methylated, or hydroxylatedforms. The fatty acid salts of the subject invention can be representedby the following formula:

    R.sub.1 Y.sub.1 Y.sub.2 COOR.sub.2

wherein

R₁ =C6 to C19 saturated or unsaturated hydrocarbon, or an epoxide, orcyclopropane thereof

Y₁ =H, C1-C5 hydrocarbon, or hydroxyl at any position along R₁

Y₂ =H, C1-C5 hydrocarbon, or hydroxyl at any position along R₁

R₂ =a salt-forming moiety chosen from the group consisting of aliphaticamines which form cationic aliphatic ammonium compounds.

Specifically exemplified herein are saturated fatty acid salts of lengthC7 to C11. The use of the compositions described here, when used in theproportions and application rates set forth more fully hereinafter,results in an unexpected herbicidal effect. Further aspects of thesubject invention are formulations and methods of formulating fatty acidherbicides which facilitate the preparation of fatty acid herbicidalcompositions without the use of surfactants. Also disclosed areprocedures for preventing the formation of fatty acid esters in acomposition comprising a fatty acid and a compound having free hydroxylgroups.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows control of barnyardgrass by various fatty acid compositionsat a 100 gpa application rate.

FIG. 2 shows control of sicklepod and barnyardgrass using either fattyacid or isopropylamine salt of fatty acid at 25 gpa application rate.

FIG. 3 shows the stability of a fatty acid in a formulation containingisopropylamine to prevent ester formation.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention pertains to the discovery of certain fatty acidsalts which have advantageous herbicidal properties. The herbicidalsalts of the subject invention can overcome many of the difficultiesdescribed in the prior art pertaining to the herbicidal use of fattyacids. Specifically, the prior art taught that salts of fatty acids havereduced herbicidal activity compared to free acids and that thepreferred herbicidal form was the free fatty acid rather than a salt.The prior art also taught that herbicidal preparations of fatty acidsmust be emulsions requiring one or more surfactants. It should be notedthat the use of surfactants with fatty acid compositions presentsdifficulties because the surfactant must not undergo chemical reactionwith the acid. Therefore, surfactants with free hydroxyl groups cannotbe used due to the potential for formation of an ester between the fattyacid and the surfactant hydroxyl group. Thus, it has been necessary tome an ester or ether as a surfactant.

We have discovered that aliphatic amine salts of fatty acids haveexcellent herbicidal activity and overcome many of the problems whichhave heretofore limited the me of fatty acids as herbicides. Thealiphatic amines of the subject invention are those which form cationicammonium salts. Whereas potassium and sodium salts of fatty acids arenot effective herbicides because of their substantially reducedherbicidal activity compared to the free fatty acid, the amine(ammonium) salts of the subject invention have excellent herbicidalactivity and solubility characteristics. We have found that aliphaticamine salts of fatty acids have herbicidal activity very similar to thefree fatty acids and often can be formulated without the use of asurfactant. Thus, the aliphatic amine salts can be provided as a"ready-to-me" salt in water soluble form with or without addition ofsurfactants, or formulated as herbicidal concentrates with a variety ofsurfactants.

The fatty acid salts used according to the subject invention can beunsubstituted, or substituted, saturated, or unsaturated, fatty acidsalts, of about C7 to about C20. Specifically exemplified are fattyacids of length C7 to C11, as typified by, but not limited to, decanoicacid or nonanoic acid. The fatty acid component of the subject inventionmay be a single fatty acid or a mixture of two or more fatty acids. Thebase used to form the salt can be an aliphatic amine or other compoundwhich would form an essentially non-polar salt of a fatty acid.Aliphatic amines which may be used to form the salt of the subjectinvention can be selected from the group including, but not limited to,tryptamine, n-amylamine, ethanolamine, n-hexylamine, sec-butylamine, orisopropylamine. A preferred example is isopropylamine. Other organicamines (or non-amine organic bases) can be used according to the subjectinvention so long as these other bases have comparable attributes ofbase strength and polarity. Further examples of the compounds which canbe used according to the subject invention include, but are not limitedto, the alkyl amines, alkylene amines and alkanol amines containing notmore than 2 amine groups, such as methylamine, ethylamine,n-propylamine, isopropylamine, n-butylamine, isobutylamine,sec-butylamine, n-amylamine, isoamylamine, hexylamine, heptylamine,octylamine, nonylamine, decylamine, undecylamine, dodecylamine,tridecylamine, tetradecyclamine, pentadecylamine, hexadecylamine,heptadecylamine, octadecylamine, methylethylamine, methylisopropylamine,methylhexylamine, methylnonylamine, methylpentadecylamine,methyloctadecylamine, ethylbutylamine, ethylheptylamine,ethyloctylamine, hexylheptylamine, hexyloctylamine, dimethylamine,diethylamine, di-n-propylamine, diisopropylamine, di-n-amylamine,diisoamylamine, dihexylamine, diheptylamine, dioctylamine,trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine,tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tri-n-amylamine,ethanolamine, n-propanolamine, isopropanolamine, diethanolamine,N,N-diethylethanolamine, N-ethylpropanolamine, N-butylethanolamine,allylamine, n-butenyl-2-amine, n-pentenyl-2-amine, n-hexenyl-2-amine,and proeylenediamine; primary aryl amines such as aniline,methoxyaniline, ethoxyaniline, o,m,p-toluidine, phenylenediamine,2,4,6-tribromoaniline, benzidine, naphthylamine, o,m,p-chloroaniline,and the like; and hetrocyclic amines such as pyridine, morpholine,piperidine, pyrrolidine, indoline, azepine and the like. Further, thesalts formed according to the subject invention can be, for example,from the group consisting of monoalkylammonium, dialkylammonium,trialkylammonium, monoalkenylammonium, dialkenylammonium,trialkenylammonium, monoaklynylammonium, dialkynylammonium,trialkynylammonium, monoalkanolammonium, dialkanolammonium, andtrialkanolammonium.

Following are examples which illustrate procedures, including the bestmode, for practicing the invention. These examples should not beconstrued as limiting. All percentages are by weight and all solventmixture proportions are by volume unless otherwise noted.

EXAMPLE 1

A ready-to use aqueous formulation of the isopropylamine salt ofpelargonic (nonanoic) acid was prepared. The pelargonic acid wasobtained as "EMERY 1202" from Quantum Chemical Corporation, Cincinnati,Ohio, and is a mixture of normal fatty acids of chain length 8, 9, and10, with C9 being predominant. Various aqueous formulations wereprepared with up to 20% active ingredient as the fatty acid and up to 6%isopropylamine, with the balance being water. The requisite amount ofpelargonic acid was dispensed into an appropriate mixing vessel and themixing initiated. The requisite amount of water was added to the acidand the acid dispersed into the water by mixing, thus forming a cloudy,unstable dispersion. Isopropylamine (ALDRICH Chemical Company,Milwaukee, Wis.) was added slowly, with continuous mixing, in sufficientquantity to bring the pH of the formulation to approximately 7.4-7.8. Atthis approximate pH the cloudy dispersion became translucent as thefatty acid isopropylamine salt became water soluble. By employing theproportions of acid to isopropylamine described here, formulations of upto about 75% fatty acid can be prepared by this method.

An aqueous formulation prepared as described above and containing 4%fatty acid and isopropylamine was applied to barnyardgrass and sicklepodplants. These plants had been grown in a greenhouse in a soil-lesspotting mix (PROMIX) to the 2-3 true leaf stage. The application wasmade using a hand-held atomizer (CROWN Industrial Sprayers, Hebron,Ill.), and the aqueous formulation was applied to run-off (approx. 250gallons per acre). Two days after treatment the plants were completelykilled by the application.

Although surfactants are not necessary according to the methods orcompositions of the subject invention, the formulations described hereindo not preclude the addition of surfactants. For example, a surfactantmay be useful when utilizing certain organic amine salts with lowersolubility characteristics than those specifically exemplified herein.Also, as would be readily apparent to a person skilled in the art, theexact pH needed for optimum solution may vary with the organic amineemployed. The optimum pH could be readily determined by a person skilledin this art.

EXAMPLE 2

Greenhouse trials were carried out to demonstrate the herbicidalactivity obtained by application of a fatty acid organic amine salt.Barnyardgrass was planted into 2×2 in pots in a soil-less potting mix(PROMIX) and was cultivated in a greenhouse maintained at daytimetemperatures of 70°-90° F., and was watered by sub-irrigation tomaintain vigor. Plants were treated at the 2-3 true leaf stage.

Herbicidal concentrates of a free fatty acid, a saponified potassiumsalt, and an isopropylamine salt were prepared. Pelargonic acid wasformulated according to mixing methods well known to practitioners inthe an and using surfactants such as those disclosed in U.S. Pat. No.4,975,110. Pelargonic acid was obtained as "EMERY 1202" from QuantumChemical Corporation, Cincinnati, Ohio. An emulsifiable concentratecontaining 60% by weight pelargonic acid was prepared in an emulsionsystem of 9% by weight "BRIJ 58" (ICI AMERICAS, INC, Wilmington, Del.),0.5% by weight "RENNEX-31" (ICI), with the balance being ethyleneglycol. A potassium salt concentrate was prepared as above, butcontained approximately 20% by weight KOH with the ethylene glycoladjusted accordingly. An isopropylamine salt was likewise prepared withapproximately 16% by weight isopropylamine with the ethylene glycoladjusted accordingly. A quantity of each of these 60% fatty acidconcentrates was diluted with sufficient water to prepare an aqueousmixture containing 4% active ingredient calculated as the fatty acid.These mixtures, and appropriate dilutions thereof, were applied tobarnyardgrass plants using a track sprayer calibrated to deliver thefield equivalent of an application rate of 100 gallons per acre (gpa).After treatment the plants were removed to the greenhouse and maintainedunder good growth conditions.

At 4 days after treatment (DAT), the plants were rated to determineherbicidal effects. Weed control ratings ascertained the extent ofcontrol, i.e., reduction in growth, obtained and scored on the basis of0 to 100 where 100 represents complete killing of the plants and 0represents no reduction in growth, as compared to the untreated check.

FIG. 1 illustrates the weed control obtained with the free acid, and theloss of weed control typically observed when the free fatty acid issaponified, e.g., convened to the potassium salt. The isopropylaminesalt produced a herbicidal effect more like that obtained with the freeacid than that obtained with the saponified salt.

EXAMPLE 3

Another greenhouse trial was conducted to compare the isopropylaminesalt to the free fatty acid at a low delivery volume (25 gpa).Barnyardgrass and sicklepod were cultivated in the greenhouse asdescribed above. Plants were treated at the 2-3 true leaf stage. Thefree fatty acid and the isopropylamine salt mixtures were prepared inwater by dilution of the appropriate concentrates, as described above,and applied to the plants in a track sprayer at the field equivalent of25 gpa. After application, plants were returned to the greenhouse andmaintained under good growing conditions. Herbicidal effects wereassessed as described above at 4 DAT.

FIG. 2 illustrates the herbicidal effects of the free fatty acid and theisopropylamine salt on barnyardgrass and sicklepod at an applicationdelivery rate of 25 gpa.

EXAMPLE 4

Greenhouse trials were carried out to demonstrate the herbicidalactivity obtained following application of fatty acid salts of severalorganic amines. Florida beggarweed, velvetleaf, barnyardgrass, andcrabgrass were used in these experiments. These weeds were planted in2×2-inch pots in a soft-less potting mix (PROMIX) and were cultivated ingreenhouses that were maintained at daytime temperatures of 70°-90° F.,and were watered by sub-irrigation to maintain vigor. Plants weretreated at the 2-3 true leaf stage.

The fatty acid organic amine salt formulations were prepared by standardprocedures similar to those described above, but with the followingmodifications: the sec-butylamine salt was approximately 19% by weightof the organic amine; the tryptamine salt, 20%; n-amylamine salt, 16%;n-hexylamine salt, 14%; and ethanolamine salt, 10%. Aqueous mixturesderived from these formulation concentrates were prepared at a 2% activeingredient rate, calculated as the free acid, by appropriate dilution inwater. The test mixtures were applied to plants in a track sprayerdelivering the field equivalent of 100 gpa. After application, plantswere returned to the greenhouse and maintained under good growingconditions. Herbicidal effects were assessed as described above 4 DAT.Tables 1 and 2 show the herbicidal effects of the fatty acid organicamine salts.

                  TABLE 1                                                         ______________________________________                                        Weed control with 2% active ingredient solutions applied at 100               gpa                                                                                    Percent Control                                                                 Florida                                                            Formulation                                                                              beggarweed  Velvetleaf                                                                             Barnyardgrass                                 ______________________________________                                        Acid       90          95       85                                            Potassium salt                                                                           50          20       20                                            Isopropylamine                                                                           90          90       80                                            salt                                                                          sec-Butylamine                                                                           90          85       85                                            ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Weed control with 2% active ingredient solutions applied at 100               gpa                                                                                     Percent Control                                                                 Florida                                                           Formulation beggarweed  Velvetleaf                                                                             Crabgrass                                    ______________________________________                                        Acid        100         100      98                                           Tryptamine salt                                                                           85          50       70                                           n-amylamine salt                                                                          100         90       90                                           n-hexylamine salt                                                                         100         100      95                                           ethanolamine                                                                              100         100      98                                           ______________________________________                                    

EXAMPLE 5

Herbicidal fatty acid emulsifiable concentrates were prepared in asolvent base containing ethylene glycol. The concentrates had as a baseformulation, by weight, 60% pelargonic acid, 9% "BRIJ 58," 0.5%"RENNEX-31" (ICI) with the balance being ethylene glycol. As suggestedin U.S. Pat. No. 4,975,110, over time the pelargonic acid was found toreact with the hydroxyl groups of the ethylene glycol solvent to formthe ethylene glycol ester of pelargonic acid. This reaction can befollowed easily by base titration of the residual free fatty acid; asthe ester forms, the amount of free fatty acid diminishes. The rate ofreaction can be increased in accelerated stability studies performed at40° C., and the combination of the titration method and the acceleratedstability method can be used to evaluate modifications to theformulation which are made in an attempt to limit the amount of esterformed. A second emulsifiable concentrate was prepared as describedabove, but containing by weight, 60% pelargonic acid, 9% "BRIJ 58," 0.5%"RENNEX-31," 10% isopropylamine, 3% water, with the balance beingethylene glycol. FIG. 3 illustrates the stability of the fatty acid in aformulation containing isopropylamine to prevent ester formation. As canbe seen from FIG. 3, the rate of ester formation from the fatty acid issubstantially reduced when the organic amine is present.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication and the scope of the appended claims.

We claim:
 1. A process for controlling unwanted vegetation, said processcomprising the application of a herbicidal composition wherein saidcomposition comprises an aliphatic ammonium salt of a fatty acid, in asuitable agricultural carrier, wherein said fatty acid salt can berepresented by the following formula:

    R.sub.1 Y.sub.1 Y.sub.2 COOR.sub.2

wherein R₁ =C7 to C11 saturated hydrocarbon, or an epoxide, orcyclopropane thereof Y₁ =H, C1-C5 hydrocarbon, or hydroxyl at anyposition along R₁ Y₂ =H, C1-C5 hydrocarbon, or hydroxyl at any positionalong R₁ R₂ =a salt-forming moiety chosen from the group consisting ofaliphatic amines which form aliphatic ammonium cations.
 2. The process,according to claim 1, wherein isopropylamine is used to form said fattyacid salt.
 3. The process, according to claim 1, wherein R₁ is C8. 4.The process, according to claim 1, wherein R₂ is an amine selected fromthe group consisting of tryptamine, n-amylamine, ethanolamine,n-hexylamine, sec-butylamine, dimethylamine, and isopropylamine.
 5. Theprocess, according to claim 4, wherein said amine is dimethylamine. 6.The process, according to claim 4, wherein said amine is ethanolamine.7. The process, according to claim 4, wherein said amine issec-butylamine.
 8. The process, according to claim 4, wherein said amineis isopropylamine.
 9. The process, according to claim 1, wherein thealiphatic ammonium cation is selected from the group consisting ofmonoalkylammonium, dialkylammonium, trialkylammonium,monoalkanolammonium, dialkanolammonium, trialkanolammonium, wherein saidaliphatic ammonium group contains from 1 to about 18 carbon atoms. 10.The process, according to claim 1, wherein a mixture of C8, C9, and C10fatty acid salts is used.
 11. The process, according to claim 1, whereinsaid composition is an aqueous solution comprising a fatty acid and analiphatic ammonium salt wherein the ratio of said fatty acid to saidaliphatic ammonium salt is approximately 3:1.
 12. The process, accordingto claim 1, wherein said composition further comprises a surfactant. 13.The process, according to claim 12, wherein said surfactant is ahydroxyl-containing surfactant.
 14. The process, according to claim 1,wherein said fatty acid ammonium salt is applied at a concentration of2%.
 15. The process, according to claim 1, wherein the application ofsaid composition results in about 80% control of the treated unwantedvegetation when a 2% active ingredient solution is applied at a rate of100 gallons per acre.
 16. The process, according to claim 1, whereinsaid process non-selectively controls unwanted vegetation.
 17. Theprocess, according to claim 1, wherein said fatty acid ammonium saltdoes not form esters when formulated with hydroxyl-containingsurfactants.
 18. A process for controlling unwanted vegetation, saidprocess comprising the application of a herbicidal composition that is atrue aqueous solution consisting essentially of a saturated aliphaticammonium salt of a C7 to C11 fatty acid, in a suitable agriculturalcarrier.